Miniature sports radar speed measuring device

Abstract

A sensor is provided for measuring the speed of a moving sports object, for example a ball such as a baseball or softball. The sensor is operable over a short range and is preferably mounted in close proximity to the path of the moving object. For measuring the speed of a ball, the sensor is preferably mounted on or in a ball glove or is otherwise mounted on the forearm of a person catching or otherwise receiving or interacting with the ball, for example, by wearing the sensor on such person's wrist. The sensor measures the speed of a ball about to be caught, for example, and displays the speed of the ball to the catching player. The sensor of the preferred embodiment utilizes CW Doppler radar in the form of a microwave radio frequency transmitter and receiver that has a single-transistor integrated antenna/oscillator. A simple, low cost unit having a low radiation and low energy consumption transmitter, receiver and signal processor, is provided.

Accordingly, the following is claimed: 
     
       1. A self-contained self-powered ball speed measuring device that is capable of being mounted, when in use, on the forearm of the catching arm of a person catching the ball, the device comprising: a self-contained speed determining unit including: an RF microwave homodyne circuit that includes a single transmit/receive-oscillator/detector/antenna configured to transmit an RF signal generally toward a forward side of the unit and to receive the signal when reflected from and Doppler-shifted by a ball moving toward the unit on the forward side thereof,   a filter circuit connected to the homodyne circuit and effective to limit the received signal to frequencies within a limited band,   a signal processor configured to measure a Doppler frequency of the limited received Doppler shifted-signal and including a digital processor programmed to calculate the speed of the moving ball from the measured Doppler frequency,   a display connected to the signal processor and operable to display the calculated speed in a direction viewable by the person catching the ball, and   a self contained source of electrical energy sufficient to power the circuits, the processor and the display; and     a securement connected to the unit and configured to support the unit on the forearm of the person catching the ball such that the RF circuit is directed toward the moving object and such that the display is perceivable by such person.   
     
     
       2. The system of claim 1 wherein the user is a person catching the object and wherein: the securement includes structure connecting the unit to a glove configured to be worn on a catching arm of the user such that the RF circuit is directed toward the moving object and such that the display is perceivable by the user.   
     
     
       3. The system of claim 1 wherein the object is a ball, the user is a person catching the ball, and wherein: the securement is a ball glove configured to be worn on a catching arm of the person catching the ball, the securement including mounting structure for securing the unit such that the RF circuit is directed toward the moving ball and such that the display is perceivable by the person catching the ball.   
     
     
       4. The system of claim 1 wherein the user is a player interacting with the object and wherein: the securement is a wrist band configured to be worn on an arm of the player, the securement including mounting structure for securing the unit such that the RF circuit is directed toward the moving object.   
     
     
       5. The system of claim 1 wherein the unit further includes: a timing circuit connected to the energy source and operable automatically reduce power to the RF circuit of the unit following each use of the unit to measure the speed of an object.   
     
     
       6. The system of claim 1 further comprising: a user actuatable switch connected to the energy source and operable to apply power to the RF circuit of the unit prior to a use of the unit to measure the speed of an object.   
     
     
       7. The system of claim 1 further comprising: a user actuatable switch connected to the processor and operable to select a measurement unit mode of the display; and   the processor being operable in response to the switch to calculate the speed and control the display in accordance with the selected measurement unit mode.   
     
     
       8. The device of claim 1 further comprising: a user actuatable switch connected to the processor to select a mode of the display; and   the processor being operable in response to the switch to calculate the speed and control the display in accordance with the selected mode.   
     
     
       9. The device of claim 1 wherein: the self-contained speed determining unit has a range of effectiveness of not more than approximately ten feet.   
     
     
       10. The device of claim 1 wherein: the transmit/receive--oscillator/detector/antenna of the RF microwave homodyne circuit is a single transistor single transmit/receive--oscillator/detector/antenna.   
     
     
       11. The device of claim 1 wherein: the self-contained speed determining unit further includes at least one switching element connected between the energy source and the homodyne circuit and operable to energize the transmit/receive-oscillator/detector/antenna of the homodyne circuit to transmit the signal and then to automatically disable the transmit/receive-oscillator/detector/antenna of the homodyne circuit from transmitting the signal after being energized for a predetermined interval of time while the energy source continues to power the display to hold a display of the calculated speed thereon.   
     
     
       12. The device of claim 1 wherein: design parameters of the speed determining unit are selected such that a Doppler shifted signal received solely from a ball moving within three feet of the device contains sufficient information for the calculation of the speed of the moving ball.   
     
     
       13. The device of claim 1 wherein: the signal processor is configured to produce a plurality of Doppler frequency measurements from the signal reflected from the moving ball and to compare the measurements and thereby determine the validity of the received signal as a signal Doppler-shifted by the motion of the ball.   
     
     
       14. A self-contained self-powered ball speed measuring device that is capable of being mounted, when in use, on the forearm of the catching arm of a person catching the ball, the device comprising: a self-contained speed determining unit having a range of effectiveness of not more than approximately ten feet and including: an RF microwave homodyne circuit that includes a single transistor single transmit/receive-oscillator/detector/antenna configured to transmit an RF signal generally toward a forward side of the unit and to receive the signal when reflected from and Doppler-shifted by a ball moving toward the unit on the forward side thereof,   a filter circuit connected to the homodyne circuit and effective to limit the received signal to frequencies within a limited band,   a signal processor configured to measure a Doppler frequency of the limited received Doppler shifted-signal and including a digital processor programmed to calculate the speed of the moving ball from the measured Doppler frequency,   a display connected to the signal processor and operable to display the calculated speed in a direction viewable by the person catching the ball, and   a self contained source of electrical energy sufficient to power the circuits, the processor and the display,   at least one switching element connected between the energy source and the homodyne circuit and operable to energize the transmit/receive-oscillator/detector/antenna of the homodyne circuit to transmit the signal and then to automatically disable the transmit/receive-oscillator/detector/antenna of the homodyne circuit from transmitting the signal after being energized for a predetermined interval of time while the energy source continues to power the display to hold a display of the calculated speed thereon; and     a securement connected to the unit and configured to support the unit on the forearm of the person catching the ball such that the RF circuit is directed toward the moving object and such that the display is perceivable by such person.   
     
     
       15. The system of claim 14 wherein the user is a person catching the object and wherein: the securement includes structure connecting the unit to a glove configured to be worn on a catching arm of the user such that the transmitter-receiver is directed toward the moving object and such that the display is perceivable by the user.   
     
     
       16. The system of claim 14 wherein the user is a player interacting with the object and wherein: the securement is a wrist band configured to be worn on an arm of the player, the securement including mounting structure for securing the unit such that the transmitter-receiver is directed toward the moving object.   
     
     
       17. The device of claim 14 wherein: design parameters of the speed determining unit are selected such that a Doppler shifted signal received solely from a ball moving within three feet of the device contains sufficient information for the calculation of the speed of the moving ball.   
     
     
       18. The device of claim 14 wherein: the signal processor is configured to produce a plurality of Doppler frequency measurements from the signal reflected from the moving ball and to compare the measurements and thereby determine the validity of the received signal as a signal Doppler-shifted by the motion of the ball.